Peripherally, skeletal muscle mitochondria increase in size and number, and the content of oxidative enzymes is augmented. In addition, muscle fiber myoglobin concentration increases and the density of capillaries surrounding the cells rise. These peripheral changes increase the ability of the tissue to use O2, and are responsible for elevating A-V O2 diff. Trained individuals also have greater muscle glycogen and are able to tolerate higher blood lactate levels. Click here for a summary of training effects.
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